Physical Characteristics

The adult roof rat, also known as the black rat, ship rat, house rat, Alexandrine rat and old English rat, is about 14 inches long, with a body length of six inches and a tail length of eight inches. Fur is soft, and color can be sooty black on the back and gray underneath (black rat) or brown intermixed with gray above and an underside of yellow-white (Alexandrine rat), depending on the subspecies. The roof rat has large ears and eyes and a pointed muzzle, and its body is sleeker than that of the Norway rat.

Roof Rat

Roof Rat


The roof rat is well known for damaging and destroying material by gnawing. It eats and contaminates stored food. Its bite is also a risk to humans, as this rat is a vector or carrier of diseases – historically, bubonic plague, but in modern times, salmonellosis, leptospirosis (aka Weil’s disease) and trichinosis (spread to pigs, which infect humans). The roof rat is nocturnal and, unlike the mouse, it will shun new objects introduced into its territory. This rat’s nesting preference is in the upper parts of structures, but it also has been found in basements as well as outdoors in trees. Its lifespan is around one year, and in that time, a female will bear two to four litters, each with five to seven pups. Once the roof rat has established a harborage, it tends to follow the same route to its food and/or water source, keeping its path clear of debris. A roof rat will feed on practically anything, but it prefers seeds, nuts, fruits and berries when in season. It also may feed on snails, slugs, and the American, brown and smokybrown cockroach. Near waterways, the roof rat may feed on fish, shellfish and other aquatic animals.


Once you’ve identified the roof rat as your pest, you’ll want to clean up any sources for its food and water, deprive it of harborage, and rat-proof your home or place of business. Keep in mind that a 1/2 inch opening gives a rat enough wiggle room to enter. Rat droppings and rub marks along walls will indicate high-traffic areas. If you set up traps, place them along walls, and use baits that it likes – nuts and grains will work. One problem with bait stations that deliver a rodenticide is that some rats that consume the poison may climb inside walls or inaccessible areas before they die, and will not only smell bad while decomposing, but their corpses create food and harborage for developing insect larvae. Call Clark Pest Control, and a technician will come to your home or place of business with the answer to your rat problem.

Latin name: Rattus rattus